1. Field of the invention
The present invention relates to an elevator control apparatus, and particularly, to an elevator control apparatus capable of automatically effecting a slow-speed rescue operation after a safety circuit of the apparatus has operated.
2. Description of the Related Art
FIG. 3 shows the construction of a conventional elevator control apparatus, such as that disclosed in Japanese Patent Laid-Open No. 2-305783. Referring to FIG. 3, the apparatus includes a safety circuit 1 for detecting abnormality of an elevator car (not shown) or other parts, a door-openable region detecting circuit 2 for determining whether or not the car is within a region within which the door of the car can be opened, a control circuit 3 using, for example, a microcomputer, and a drive device 4 for actuating a lifting motor 5 on the basis of the output of the control circuit 3. The control circuit 3 comprises an input circuit 31 connected to both the safety circuit 1 and the door-openable region detecting circuit 2, a central processing unit 32 (hereinafter abbreviated to "CPU") connected to the input circuit 31 for mutual data exchange, a memory 33 which is connected to the CPU 32 for mutual data exchange, and in which data such as a program related to the flowchart shown in FIG. 4 (described later) has previously been stored, and an output circuit 34, connected to the CPU 32 for mutual data exchange, for supplying the output of the CPU 32 to the drive device 4.
The operation of the apparatus shown in FIG. 3 will be described with reference to FIG. 4. Suppose that an abnormality has occurred during the traveling of the car, resulting in an operation of the safety circuit 1. A detection signal from the safety circuit 1 is fed to the CPU 32 via the input circuit 31, and then processed in accordance with a program already stored in the memory 33. Specifically, the CPU 32 determines whether or not the safety circuit 1 has operated, in Step S1. Since the safety circuit 1 has operated, a flag FSAFE is set to "1" in Step S2.
Subsequently, the CPU 32 determines whether or not the flag FSAFE is "1", in Step S3. Since the flag is "1", Step S4 is executed, in which a determination is made as to whether or not the car is stopped. If the car is not stopped, Step S5 is executed to determine, on the basis of the output from the door-openable region detecting circuit 2, whether or not the car is within a door-openable region. If the car is not within a door-openable region, Step S1 is again executed. If the car is within a door-openable region, Step S6 is executed, in which a stop command is given to the drive device 4 via the output circuit 34, so as to stop the motor 5, hence, stop the car, and open the door to allow passengers to get off the car, and in which restarting of the car is prohibited.
On the other hand, if the car is determined to be stopped in Step S4, CPU 32 executes Step S7 to determine, on the basis of the output from the door-openable region detecting circuit 2, whether or not the position at which the car has stopped in response to the operation of the safety circuit 1 is within a door-openable region. If that position is within a door-openable region, Step S8 is executed, in which the door is opened to allow the passengers to get off, and in which restarting of the car is prohibited. If it is determined, in Step S7, that the position at which the car is stopped is not within a door-openable region, Step S9 is executed, in which the CPU 32 commands, via the output circuit 34, the drive device 4 to perform an automatic low-speed operation, whereby the car is shifted to a rescue operation and starts traveling in this mode. When, after a car traveling in the rescue operation mode, the entrance of the car into a door-openable region has been determined in Step S5, Step S6 is executed, in which the car is stopped as described above, and the passengers are rescued at the nearest floor.
The conventional elevator control apparatus with the above-described construction entails the following problem. When the execution of a rescue operation has been determined, if the safety circuit keeps operating, the car cannot restart, thus rendering the rescue operation impossible. As a result, the passengers becomes confined in the elevator car. A method for coping with such difficulty may be adapted to simply wait for the safety circuit to return to its initial state, or to provide a plurality of rescue-operation opportunities at certain intervals of time. However, with such methods, the equipment may be damaged. If the safety circuit is actuated repeatedly, a sudden stop or the like may endanger the passengers.